• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.418-419
• /
• 2006

We investigate the influence of the ambient gas during thermal annealing on the photoluminescence (PL) properties of europium-silicate thin films. The films were fabricated on substrates by using a radio-frequency magnetron sputtering method and subsequent rapid thermal annealing (RTA). The mechanism for the formation of the europium silicates during the annealing process was investigated by using X-ray diffraction (XRD) spectroscopy, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). A series of narrow PL spectra from $Eu^{3+}$ ions was observed from the film annealed in $O_2$ ambient. Broad PL spectra associated with $Eu^{2+}$ ions, with a maximum intensity at 600 nm and a FWHM of 110 nm, were observed from the thin film annealed at $1000^{\circ}C$ in $N_2$ ambient.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.3
• /
• pp.263-267
• /
• 2007

We investigate the influence of the ambient gas during thermal annealing on the photoluminescence (PL) properties of europium-silicate thin films. The films were fabricated on substrates by using a radio-frequency magnetron sputtering method and subsequent rapid thermal annealing (RTA). The mechanism for the formation of the europium silicates during the annealing process was investigated by using X-ray diffraction (XRD) spectroscopy, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). A series of narrow PL spectra from $Eu^{3+}$ ions was observed from the film annealed in $O_2$ ambient. Broad PL spectra associated with $Eu^{2+}$ ions, with a maximum intensity at 600 nm and a FWHM of 110 nm, were observed from the thin film annealed at $1000^{\circ}C$ in $N_2$ ambient.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.11
• /
• pp.1020-1024
• /
• 2006

Europium$(Eu^{2+}\;or\;Eu^{3+})$-activated calcium aluminium silicate phosphors were synthesized for the first time and the structures and luminescence characteristics of these phosphors were investigated. The phosphors in this study emitted blue, green, and even red light depending on the starting milterials and annealing conditions for synthesis. In addition, the structure was also changed when the different starting materials were used. When $CaCO_3$ was used as a starting material, tetragonal $Ca_2Al_2SiO_7$ was formed. However, pure green light was emitted when the annealing was conducted in reduced atmosphere and red one was emitted by annealing in air. In the case of $CaSiO_3$ as a starting material, triclinic $CaAl_2Si_2O_8$ was formed and only pure blue emission was observed. Moreover, this blue phosphor exhibited higher intensity than that of commercial YAG:Ce phosphor, which showed the possibility of application on the phosphor for new light source such as a UV-LED.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.430-431
• /
• 2009

In this study, europium doped strontium silicate ($Sr_2SiO_4:Eu^{2+}$) phosphor has been synthesized by conventional solid-state method and investigated luminescent characteristic. $SrCO_3$ and $SiO_2$ were mixed together by 2:1 mole ratio. Also $NH_4Cl$ was added as a flux. The mixture were sintered at $800^{\circ}C$, $1000^{\circ}C$ for 3h under the atmosphere (5% $H_2$/95% $N_2$). This phosphor can be applicated to the yellow phosphor for white LED because it has yellow emission band (540nm), which emits efficiently under the 370nm excitaion energy.

• Journal of the Korean Chemical Society
• /
• v.50 no.2
• /
• pp.137-140
• /
• 2006

In this report, Europium doped strontium barium gallium silicate ((Sr,Ba)2Ga2SiO7:Eu2+) phosphor has been synthesized by conventional solid-state method and investigated luminescent characteristic. Appropriate proportions of the raw materials were mixed in an agate mortar with acetone to obtain starting mixtures. Also, this phosphor was prepared by simple process under the reduction atmosphere (25% H2/75% N2). This phosphor can be applicated to the green phosphor for white LED because it has green emission band (513 nm), which emits efficiently under the 405nm excitation energy.

• Applied Chemistry for Engineering
• /
• v.25 no.5
• /
• pp.455-462
• /
• 2014

This work investigated the hydrophobic coating of silicate yellow phosphor powder in the form of divalent europium-activated strontium orthosilicate ($Sr_2SiO_4:Eu^{2+}$) by using an atmospheric pressure dielectric barrier discharge (DBD) plasma with argon as a carrier and hexamethyldisiloxane (HMDSO), toluene and n-hexane as precursors. After the plasma treatment of the phosphor powder, the lattice structure of orthosilicate was not altered, as confirmed by an X-ray diffractometer. The coated phosphor powder was characterized by scanning electron microscopy, fluorescence spectrophotometry and contact angle analysis (CAA). The CAA of the phosphor powder coated with the HMDSO precursor revealed that the water contact angle increased from $21.3^{\circ}$ to $139.5^{\circ}$ (max. $148.7^{\circ}$) and the glycerol contact angle from $55^{\circ}$ to $143.5^{\circ}$ (max. $145.3^{\circ}$) as a result of the hydrophobic coating, which indicated that hydrophobic layers were successfully formed on the phosphor powder surfaces. Further surface characterizations were performed by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry, which also evidenced the formation of hydrophobic coating layers. The phosphor coated with HMDSO exhibited a photoluminescence (PL) enhancement, but the use of toluene or n-hexane somewhat decreased the PL intensity. The results of this work suggest that the DBD plasma may be a viable method for the preparation of hydrophobic coating layer on phosphor powder.